There was a pissing contest thread about this exact topic recently.
Do a search. Fundamentally, it allows quicker articulation of the front suspension. This helps transfer weight to the rear and improves the total traction available at the rear tires.
People take off their front sway bars for drag racing. It takes of weight something around 25 lbs or so and it takes it off where we need it most which is the front end. You can take it off and leave it off if you dont do any aggressive driving like on road racing tracks and as long as you arent really agressive when you turn your car when daily driving. I dont think it matters all that much. I am ditching my here b4 i go to the track next and plan on just leaving it off for the rest of eternity.